According to this article
She has spoken to the FBI, telling investigators that she accompanied Mateen to the Pulse nightclub at least once before the massacre.
She also said she drove with him to purchase ammunition, and pleaded with him not to commit the shooting.
Salman has not been arrested, but if she had knowledge of the plot and failed to alert law enforcement, she could face criminal charges, including the intentional concealing of knowledge of a felony, aiding and abetting a crime, or even conspiracy to commit an act of terrorism, depending on her level of culpability. Federal authorities reportedly convened a grand jury in Florida on Wednesday to help investigate the shooting, and that would be a vehicle for filing federal charges against Salman.
Here's what we know about Noor Salman, the widow of the Orlando gunman - LA Times
I do believe she knew something and to be completely honest, I have no ideas why she has not been arrested.
I don't believe government should target family members because I don't believe people should be punished by perfect hindsight. I also don't believe in guilt by association.
Now, If you follow international news, you may have heard about how totalitarian states like North Korea punish political dissent. The process usually involves rounding up the offender plus all his family members and summarily executing them. The lucky ones get shipped off to prison camps for “re-education.” Fortunately, such guilt by association doesn’t exist in the American criminal justice system.
From a legal standpoint, the difference between guilt by association in criminal vs. security clearance cases is clear: the former is a deprivation of a constitutional right (liberty), while the latter is a privilege entirely within the government’s discretion to grant. You aren’t going to get very far arguing the constitutionality of guilt by association in a security clearance denial case. Fortunately, even if you do have some bad apples in the family, the cause is not lost.
All these being said, I know for a fact that in some circumstances, your bad family member can affect your security clearance.
Familial bonds can sometimes cloud judgment – one of the key reasons why guilt by association is such an issue in security clearance cases. You really need to check your loyalty and judgement.
So I think it is a very complicated issue with no clear answers.
I don't think Mr. Trump is entirely wrong here if he meant "loosen the rules of engagement" in the battle field.
Just my opinion. I could be wrong though.